// #includes {{{
#include <algorithm>
#include <numeric>
#include <iostream>
#include <string>
#include <vector>
#include <queue>
#include <list>
#include <deque>
#include <stack>
#include <set>
#include <map>
#include <cstdio>
#include <cstdlib>
#include <cassert>
#include <cstring>
#include <cmath>
using namespace std;
// }}}
// pre-written code {{{
#define REP(i,n) for(int i=0;i<(int)(n);++i)
#define RREP(i,a,b) for(int i=(int)(a);i<(int)(b);++i)
#define FOR(i,c) for(__typeof((c).begin()) i=(c).begin();i!=(c).end();++i)
#define LET(x,a) __typeof(a) x(a)
//#define IFOR(i,it,c) for(__typeof((c).begin())it=(c).begin();it!=(c).end();++it,++i)
#define ALL(c) (c).begin(), (c).end()
#define MP make_pair

#define EXIST(e,s) ((s).find(e)!=(s).end())

#define RESET(a) memset((a),0,sizeof(a))
#define SET(a) memset((a),-1,sizeof(a))
#define PB push_back
#define DEC(it,command) __typeof(command) it=command

const int INF=0x3f3f3f3f;

typedef long long Int;

typedef pair<int,int> pii;

/*
#ifdef MYDEBUG
#include"debug.h"
#include"print.h"
#endif
*/
// }}}

const Int m = 1, M = 1000000000000000000ll;

int main(){
	int n;
	cin>>n;
	vector<Int> b(n);
	REP(i,n)cin>>b[i];
	pair<Int,Int> v(0,1);//const, a_0
	pair<Int,Int> rng(m,M);
	Int a;
	REP(i,n){
		//judge
		pair<Int,Int> v2;
		if(i%2==0){
			v2.first = -v.first;
			v2.second = -v.second;
			v2.first+=b[i];
		}else{
			v2.first = v.first;
			v2.second = v.second;
			v2.first-=b[i];
		}
//		cerr<<v2.first<<" "<<v2.second<<endl;
		v = v2;
//		cout<<v.first<<" "<<v.second<<endl;
		Int l,r;
		if(v.second==1){
			l = m-v.first, r = M-v.first;
		}else if(v.second==-1){
			l = v.first-M, r = v.first-m;
		}
		rng.first=max(rng.first,l);
		rng.second=min(rng.second,r);
		if(rng.first>rng.second){
			cout<<-1<<endl;
			return 0;
		}
		if(i==n-1)a = rng.first;
	}
	cout<<n+1<<endl;
	REP(i,n){
		cout<<a<<endl;
		assert(m<=a and a<=M);
		if(i%2==0){
			a = b[i] - a;
		}else{
			a = a - b[i];
		}
	}
	cout<<a<<endl;
	assert(m<=a and a<=M);

	return 0;
}